Respiratory-gated 18F Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Imaging in Evaluation of Primary Gastric Lesions and Gastric Lymph Nodes in Patients with Gastric Cancer.

AIMS: To evaluate the added value of respiratory-gated positron emission tomography (PET) in 18F fluorodeoxyglucose (FDG) PET/magnetic resonance imaging (MRI) in the visual and semi-quantitative assessment of primary gastric lesions and gastric lymph nodes for patients with gastric cancer. MATERIALS AND METHODS: In total, 102 upper abdominal respiratory-gated and whole-body 18F FDG PET/MRI of 88 patients with gastric cancer were evaluated visually and semi-quantitatively. For 41 patients who underwent surgery, histopathological and PET findings were compared. Three PET images were obtained from upper abdominal PET data: non-Q static (non-QS) PET from all counts, respiratory-gated Q static (QS) PET from counts in the end-expiration phase of breathing, shortened 4 min (S4min) PET that was reconstructed to obtain similar counts to QS PET. The semi-quantitative parameters (standardised uptake values, metabolic tumour volume, total lesion glycolysis) of primary lesions for each PET image, the sizes of primary lesions and the patient's body mass index were recorded. According to lymph node stations, the presence and numbers of positive lymph nodes and visual scores of lymph nodes for each PET image were recorded. RESULTS: The patients with smaller gastric lesions (≤30 mm) or higher body mass index (>30) had significantly higher standardised uptake value percentage changes in QS PET compared with non-QS PET (all P < 0.05). The third (lesser curvature), fourth (greater curvature) and sixth (infra-pyloric) lymph node stations had significantly higher visual scores in the QS PET than in the others. The fourth lymph node station had a significantly higher number of FDG-positive lymph node in the QS PET than in the non-QS and the whole-body PET images. In the fourth station, sensitivity, positive predictive value, negative predictive value and accuracy increased in the QS PET compared with the others. CONCLUSION: Respiratory-gated PET/MRI was found to be significantly superior in the evaluation of especially the fourth lymph node station, smaller gastric lesions and in the patients with a higher BMI compared with the non-respiratory-gated PET images.

Texture features of primary tumor on 18F-FDG PET images in non-small cell lung cancer: The relationship between imaging and histopathological parameters. / Características de textura del tumor primario en imágenes de 18F-FDG PET en cáncer de pulmón de células no pequeñas: la relación entre parámetros de imágenes y parámetros histopatológicos.

OBJECTIVES: The aims of this study were to evaluate the relationships between textural features of the primary tumor on FDG PET images and clinical-histopathological parameters which are useful in predicting prognosis in newly diagnosed non-small cell lung cancer (NSCLC) patients. MATERIAL AND METHODS: PET/CT images of ninety (90) patients with NSCLC prior to surgery were analyzed retrospectively. All patients had resectable tumors. From the images we acquired data related to metabolism (SUVmax, metabolic tumor volume [MTV] and total lesion glycolysis [TLG]) and texture features of primary tumors. Histopathological tumor types and subgroups, degree of Ki-67 expression and necrosis rates of the primary tumor, mediastinal lymph node (MLN) status and nodal stages were recorded. RESULTS: Among the 2histologic tumor types (adenocarcinoma and squamous cell carcinoma) significant differences were present regarding metabolic parameters, Ki-67 index with higher values and kurtosis with lower values in the latter group. Textural heterogeneity was found to be higher in poorly differentiated tumors compared to moderately differentiated tumors in patients with adenocarcinoma. While Ki-67 index had significant correlations with metabolic parameters and kurtosis, tumor necrosis rate was only significantly correlated with textural features. By univariate and multivariate analyses of the imaging and histopathological factors examined, only gradient variance was significant predictive factor for the presence of MLN metastasis. CONCLUSIONS: Textural features had significant associations with histologic tumor types, degree of pathological differentiation, tumor proliferation and necrosis rates. Texture analysis has potential to differentiate tumor types and subtypes and to predict MLN metastasis in patients with NSCLC.

Relationship between primary lesion metabolic parameters and clinical stage in lung cancer.

OBJECTIVES: The relation of PET-derived parameters as maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), metabolic tumor volume (MTV) with clinical stage in lung cancer and correlation of SUVmax of primary tumor and that of metastatic lesion was studied in lung cancer patients. MATERIALS AND METHODS: Patients with lung cancer who were referred for FDG PET/CT were included in the study. RESULTS: PET/CT scans and pathology reports of 168 patients were assessed. A total of 146 (86.9%) of these patients had a diagnosis of non-small cell lung cancer (NSCLC) and 22 (13.1%) had small cell lung cancer (SCLC). Metabolic parameters such as SUVmax, TLG and MTV showed significant differences in all the stages in NSCLC patients (p<0.001). However, after tumors sizes <25 mm were excluded, no significant differences in SUVmax between stages were observed. No significant differences were found between these metabolic parameters and limited or extended disease SCLC. Tumor diameter correlated with primary tumor SUVmax and significant correlations between primary lesion SUVmax and metastatic lesion SUVmax were found. CONCLUSIONS: Although differences were found regarding indices between stages of NSCLC cases, SUVmax differences between stages seem to be caused by underestimation of SUVmax in small lesions. Other glucose metabolism indexes such as MTV and TLG show promising results in terms of prognostic stratification. Future studies are needed for better understanding of their contribution to clinical cases.

Relación del ciclo clínico con los parámetros metabólicos de la lesión primaria en el cáncer de pulmón / Relationship between primary lesion metabolic parameters and clinical stage in lung cancer

Objetivo: En pacientes con cáncer de pulmón hemos investigado la relación de los parámetros PET como el valor máximo estandarizado de captación (SUVmax), la glucólisis lesional total (TLG) y el volumen tumoral metabólico (MTV) con el estadio clínico y la correlación del SUVmax del tumor primario con el SUVmax de las metástasis. Material y métodos: El estudio incluyó pacientes con cáncer de pulmón enviados para realizar una estadificación con FDG PET/TC. Resultados: Se estudiaron las imágenes PET/TC y los informes anatomopatológicos de 168 pacientes. De los 168 pacientes, 146 (86,9%) tenían cáncer pulmonar de células no peque˜nas (CPCNP) y 22 (13,1%) cáncer pulmonar de células peque˜nas (CPCP). En todos los estadios de los pacientes con CPCP se detectaron diferencias significativas (p < 0,001) en el SUVmax, la TLG y el MTV. Sin embargo, al excluir los tumores de un tama˜no inferior a 25 mm, no se encontró una diferencia significativa en el SUVmax de los diferentes estadios. No se encontraron diferencias significativas entre estos parámetros metabólicos y la enfermedad limitada o extendida del CPCP. El diámetro del tumor se correlacionó con el SUVmax del tumor primario y se obtuvieron diferencias significativas entre el SUVmax del tumor primario y el SUVmax de las metástasis en todo el conjunto de pacientes. Conclusiones: Aunque se encontraron diferencias en los índices metabólicos entre los distintos estadios del CPCNP, las diferencias de SUVmax en los diferentes estadios parecen ser resultado de una infraestimación del SUVmax en las lesiones peque˜nas. Otros índices del metabolismo de la glucosa, como el MTV y la TLG, muestran resultados prometedores de cara a una estratificación pronóstica y se deberían realizar futuros estudios para alcanzar un mejor conocimiento de su contribución clínica (AU)

Objectives. The relation of PET-derived parameters as maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), metabolic tumor volume (MTV) with clinical stage in lung cancer and correlation of SUVmax of primary tumor and that of metastatic lesion was studied in lung cancer patients. Materials and methods. Patients with lung cancer who were referred for FDG PET/CT were included in the study. Results. PET/CT scans and pathology reports of 168 patients were assessed. A total of 146 (86.9%) of these patients had a diagnosis of non-small cell lung cancer (NSCLC) and 22 (13.1%) had small cell lung cancer (SCLC). Metabolic parameters such as SUVmax, TLG and MTV showed significant differences in all the stages in NSCLC patients (p < 0.001). However, after tumors sizes <25 mm were excluded, no significant differences in SUVmax between stages were observed. No significant differences were found between these metabolic parameters and limited or extended disease SCLC. Tumor diameter correlated with primary tumor SUVmax and significant correlations between primary lesion SUVmax and metastatic lesion SUVmax were found. Conclusions. Although differences were found regarding indices between stages of NSCLC cases, SUVmax differences between stages seem to be caused by underestimation of SUVmax in small lesions. Other glucose metabolism indexes such as MTV and TLG show promising results in terms of prognostic stratification. Future studies are needed for better understanding of their contribution to clinical cases (AU)